1. Field of the Invention
The present invention relates to synthesis of ammonia by contacting ammonia synthesis gas with an ammonia catalyst with ruthenium as the active catalytic material supported on a metal nitride carrier.
2. Description of the Related Art
Ruthenium based catalysts for use in the synthesis of ammonia from ammonia synthesis gas are known in the art (U.S. Pat. No. 4,600,571, JP Patent Publication No. 9168739 and GB Patent No. 2,033,766)
In order to minimise the necessary amount of expensive ruthenium such catalysts are usually supported on a carrier material to maximise the accessible surface area of the active ruthenium particles.
Several supports have been proposed as suitable in catalytic ammonia synthesis, those are MgO, Al2O3 and MgAl2O4. At present the most active ruthenium catalysts are those being supported on graphitised carbon as carrier material.
However, a severe drawback in using carbon-based support is susceptibility to hydrogenation under industrial conditions. The carbon support transforms slowly into methane resulting in a gradual loss of the support and eventually into operating difficulties.